Build results: mc.freebsd

Build results: mc.freebsd

[FAIL] 9fef96e3fc0e48ed435bda6345c0a50b1876a436

Use zalloc to allocate livedense and livesparse
Although the data structure works no matter the initial contents of
livedense and livesparse, malloc returns a pointer to indeterminate
values, and accessing an indeterminate value is undefined behavior.
This also avoids spurious valgrind errors when debugging.